The aim of this protocol remains to try to elucidate the biochemical and cellular mechanisms by which fiber and fat influence the growth, and in some cases the abnormal cancerous growth of the epithelial cells of the colon. Epidemiological evidence clearly indicates that both of these dietary factors play a role in normal colon function and malignant transformation, but the mechanisms of action remain obscure. The approach is to feed normal human volunteers liquid formula diets and to vary the composition of these diets with respect to fat or fiber content and correlate such changes with alterations in specific mRNAs obtained from colon biopsy specimens. The rate of accrual of human subjects who are willing to participate remains slow, but since the onset of this protocol in March 1995, 7 patients have successfully completed this protocol. All biopsies are being stored in liquid nitrogen pending batch analysis. Future plans are to continue to enroll patients until 8 have been accumulated in each experimental group.